60 research outputs found
Integral measurement of the 12C(n, p)12B reaction up to 10 GeV
The integral measurement of the 12C(n, p)12B reaction was performed at the neutron time-offlight facility n TOF at CERN. The total number of 12B nuclei produced per neutron pulse of the n TOF
beam was determined using the activation technique in combination with a time-of-flight technique. The
cross section is integrated over the n TOF neutron energy spectrum from reaction threshold at 13.6 MeV
to 10 GeV. Having been measured up to 1 GeV on basis of the 235U(n, f) reaction, the neutron energy
spectrum above 200 MeV has been re-evaluated due to the recent extension of the cross section reference
for this particular reaction, which is otherwise considered a standard up to 200 MeV. The results from the
dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1 GeV up to 10 GeV. The
experimental results related to the 12C(n, p)12B reaction are compared with the evaluated cross sections
from major libraries and with the predictions of different GEANT4 models, which mostly underestimate
the 12B production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters.European Atomic Energy Communitys (Euratom) Seventh Framework Programme FP7/2007-2011-CHANDA (No. 605203)Narodowe Centrum Nauki (NCN)-UMO-2012/04/M/ST2/00700Croatian Science Foundation-No. 168
Preparation and characterization of 33-S samples for 33-S(n,alpha)30-Si cross-section measurements at the n_TOF facility at CERN
Thin 33S samples for the study of the 33S(n,a)30Si cross-section at the n_TOF facility at CERN were made by thermal evaporation of 33S powder onto a dedicated substrate made of kapton covered with thin layers of copper, chromium and titanium. This method has provided for the first time bare sulfur samples a few centimeters in diameter. The samples have shown an excellent adherence with no mass loss after few years and no sublimation in vacuum at room temperature. The determination of the mass thickness of 33S has been performed by means of Rutherford backscattering spectrometry. The samples have been successfully tested under neutron irradiation.Ministerio de Economía y Competitividad de España-FPA2013-47327- C2-1-R, FPA2014-53290-C2-2-P, FPA2016-77689-C2-1-RJunta de Andalucía-P11-FQM-8229Ministerio de Economía y Empresa de España (Fondos FEDER)-FIS2015-69941-C2-1-PAECC (Asociación Española Contra el Cáncer)-PS16163811POR
High precision measurement of the radiative capture cross section of 238U at the n-TOF CERN facility
The importance of improving the accuracy on the capture cross-section of 238U has been addressed
by the Nuclear Energy Agency, since its uncertainty significantly affects the uncertainties of key design
parameters for both fast and thermal nuclear reactors. Within the 7th framework programme ANDES of the
European Commission three different measurements have been carried out with the aim of providing the
238U(n,γ) cross-section with an accuracy which varies from 1 to 5%, depending on the energy range. Hereby
the final results of the measurement performed at the n TOF CERN facility in a wide energy range from 1 eV
to 700 keV will be presented
The 236U neutron capture cross-section measured at the n-TOF CERN facility
The 236U isotope plays an important role in nuclear systems, both for future and currently operating
ones. The actual knowledge of the capture reaction of this isotope is satisfactory in the thermal region, but it is
considered insufficient for Fast Reactor and ADS applications. For this reason the 236U(n, γ) reaction crosssection has been measured for the first time in the whole energy region from thermal energy up to 1 MeV
at the n TOF facility with two different detection systems: an array of C6D6 detectors, employing the total
energy deposited method, and a 4π total absorption calorimeter (TAC), made of 40 BaF2 crystals. The two
n TOF data sets agree with each other within the statistical uncertainty in the Resolved Resonance Region up
to 800 eV, while sizable differences (up to 20%) are found relative to the current evaluated data libraries.
Moreover two new resonances have been found in the n TOF data. In the Unresolved Resonance Region up
to 200 keV, the n TOF results show a reasonable agreement with previous measurements and evaluated data
Measurement of the 241Am neutron capture cross section at the n-TOF facility at CERN
New neutron cross section measurements of minor actinides have been performed recently in order
to reduce the uncertainties in the evaluated data, which is important for the design of advanced nuclear reactors
and, in particular, for determining their performance in the transmutation of nuclear waste. We have measured
the 241 Am(n,γ) cross section at the n TOF facility between 0.2 eV and 10 keV with a BaF2 Total Absorption
Calorimeter, and the analysis of the measurement has been recently concluded. Our results are in reasonable
agreement below 20 eV with the ones published by C. Lampoudis et al. in 2013, who reported a 22% larger
capture cross section up to 110 eV compared to experimental and evaluated data published before. Our results
also indicate that the 241 Am(n,γ) cross section is underestimated in the present evaluated libraries between
20 eV and 2 keV by 25%, on average, and up to 35% for certain evaluations and energy ranges.Plan Nacional I+D+I FPA2014-53290-C2-1Comisión Europea, ANDES FP7- 249671Comisión Europea, CHANDA FP7-60520
Experimental neutron capture data of 58 Ni from the CERN n_TOF facility
The
58
Ni(
n
,
γ
) cross section has been measured at the neutron time of flight facility n_TOF at CERN, in the energy range from 27 meV up to 400 keV. In total, 51 resonances have been analyzed up to 122 keV. Maxwellian averaged cross sections (MACS) have been calculated for stellar temperatures of
k
T
=
5
–
100
keV with uncertainties of less than 6%, showing fair agreement with recent experimental and evaluated data up to
k
T
= 50 keV. The MACS extracted in the present work at 30 keV is
34.2
±
0
.
6
stat
±
1
.
8
sys
mb, in agreement with latest results and evaluations, but 12% lower relative to the recent KADoNIS compilation of astrophysical cross sections. When included in models of the
s
-process nucleosynthesis in massive stars, this change results in a 60% increase of the abundance of
58
Ni, with a negligible propagation on heavier isotopes. The reason is that, using both the old or the new MACS,
58
Ni is efficiently depleted by neutron captures.National Science Foundation (NSF) de los Estados Unidos. PHY 02-16783 y PHY 09-22648Joint Institute for Nuclear Astrophysics (JINA) de los Estados Unidos. EU MIRG-CT-2006-04652
Measurement of the neutron capture cross section of the fissile isotope 235U with the CERN n-TOF total absorption calorimeter and a fission tagging based on micromegas detectors
The accuracy on neutron capture cross section of fissile isotopes must be improved for the design
of future nuclear systems such as Gen-IV reactors and Accelerator Driven Systems. The High Priority Request
List of the Nuclear Energy Agency, which lists the most important nuclear data requirements, includes also
the neutron capture cross sections of fissile isotopes such as 233,235U and 239,241Pu.
A specific experimental setup has been used at the CERN n TOF facility for the measurement of the
neutron capture cross section of 235U by a set of micromegas fission detectors placed inside a segmented BaF2
Total Absorption Calorimeter.Plan Nacional de I+D+I Física de particulas FPA2014-53290-C2-
Integral cross section measurement of the12C(n,p)12B reaction
The integral cross section of the12C(n, p)12B reaction was measured at the neutron time of flight facility nTOF
at CERN, from the reaction threshold at 13.6 MeV up to 10 GeV, by means of the combined activation and a timeofflight
technique. The integral result is expressed as the number of12B nuclei produced per single pulse of the neutron
beam. A simple integral expression is given for calculating the number of produced12B nuclei from any given evaluated
cross section and/or model prediction. © 2015, CERN. All rights reserved.Postprint (author's final draft
High precision measurement of the radiative capture cross section of 238U at the n TOF CERN facility
The importance of improving the accuracy on the capture cross-section of 238U has been addressed by the Nuclear Energy Agency, since its uncertainty significantly affects the uncertainties of key design parameters for both fast and thermal nuclear reactors. Within the 7th framework programme ANDES of the European Commission three different measurements have been carried out with the aim of providing the 238U(n, gamma) cross-section with an accuracy which varies from 1 to 5%, depending on the energy range. Hereby the final results of the measurement performed at the n TOF CERN facility in a wide energy range from 1 eV to 700 keV will be presented.Postprint (published version
Measurement of the 241Am neutron capture cross section at the n TOF facility at CERN
New neutron cross section measurements of minor actinides have been performed recently in order to reduce the uncertainties in the evaluated data, which is important for the design of advanced nuclear reactors and, in particular, for determining their performance in the transmutation of nuclear waste.We have measured the 241Am(n,gamma ) cross section at the n TOF facility between 0.2 eV and 10 keV with a BaF2 Total Absorption Calorimeter, and the analysis of the measurement has been recently concluded. Our results are in reasonable agreement below 20 eV with the ones published by C. Lampoudis et al. in 2013, who reported a 22% larger capture cross section up to 110 eV compared to experimental and evaluated data published before. Our results also indicate that the 241Am(n,gamma ) cross section is underestimated in the present evaluated libraries between 20 eV and 2 keV by 25%, on average, and up to 35% for certain evaluations and energy ranges.Postprint (published version
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